Abstract: A surface acoustic wave device includes a piezoelectric substrate made of ?° rotated Y-cut X-propagation LiNbO3 having a cut angle ?, an IDT electrode on the piezoelectric substrate and including a plurality of electrode fingers, and a dielectric film on the piezoelectric substrate and covering the IDT electrode. The IDT electrode includes a main electrode layer and an auxiliary conductive layer. The main electrode layer is, compared to the auxiliary conductive layer, closer to a side of the piezoelectric substrate. The main electrode layer includes Pt as a main component. Where the film thickness of the main electrode layer is denoted as h, the film thickness of the dielectric film is denoted as H, and a wavelength determined by the electrode finger pitch of the IDT electrode is denoted as ?, the relationship in Formula (1) and Equation (2A) to Equation (2D) is satisfied.

Abstract: An acoustic wave device includes a piezoelectric substrate made of LiNbO3, and a dielectric film provided on the piezoelectric substrate to cover first and second IDT electrodes on the piezoelectric substrate. The first and second IDT electrodes include main electrode layers. When wave lengths determined by electrode finger pitches of the first and second IDT electrodes are ?1 and ?2, respectively, the average value thereof is ?0, ?1/?0=1+X, and ?2/?0=1?X, a relationship of 0.05?X?0.65 is satisfied. The wavelength ?1 is the longest, and the wavelength ?2 is the shortest. In Euler angles (?, ?, ?) of the piezoelectric substrate, ? is 0°±5°, ? is 0°±10°, and ? satisfies Expression 1, wherein a relationship of B1<T×r?0.10?0 and B2<T×r?0.10?0 are satisfied.

Abstract: An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer with first and second main surfaces, and a support on the second main surface, a first comb-shaped electrode on the first main surface including a first busbar and first electrode fingers connected to the first busbar and being connected to an input potential, a second comb-shaped electrode on the first main surface including a second busbar and second electrode fingers connected to the second busbar and interdigitated with the first electrode fingers, and connected to an output potential, and a reference potential electrode connected to a reference potential and including third electrode fingers on the first main surface and aligned with the first and second electrode fingers, connection electrodes connected to the third electrode fingers, respectively, and a third busbar electrically connected to the third electrode fingers by the connection electrodes.

Abstract: A bandpass acoustic wave filter device includes an IDT electrode and a dielectric film disposed on a piezoelectric substrate including a LiNbO3 layer, and an acoustic wave resonator is defined by the IDT electrode. The acoustic wave resonator utilizes the Rayleigh wave, and a response of an SH wave excited by the acoustic wave resonator is outside a pass band of the acoustic wave filter device.

Abstract: An acoustic wave device includes a support including an energy confinement layer, a piezoelectric layer on one principal surface of the support and covering the energy confinement layer, a functional electrode on one principal surface of the piezoelectric layer and at least partially overlapping the energy confinement layer, and a dielectric film on a principal surface of the piezoelectric layer on an opposite side from the energy confinement layer. The piezoelectric layer includes a functional electrode portion including the functional electrode, and a portion other than the functional electrode portion. The dielectric film is provided in at least the functional electrode portion. A thickness of a portion of the dielectric film in the functional electrode portion is larger than a thickness of the dielectric film in the portion other than the functional electrode portion.

Abstract: An acoustic wave device includes a support substrate including a space portion, a piezoelectric body layer on the support substrate, a functional electrode on the piezoelectric body layer and at least partially overlapping with the space portion in plan view along a lamination direction of the support substrate and the piezoelectric body layer, and a structure on the piezoelectric body layer and having a smaller coefficient of thermal linear expansion than the piezoelectric body layer. The structure includes a region located in a region of the piezoelectric body layer other than a region where the functional electrode is provided and that does not overlap with the space portion in the plan view.

Abstract: A composite filter device includes a piezoelectric substrate made of LiNbO3, a first filter on the piezoelectric substrate, and including acoustic wave resonators, and a second filter including one end connected in common to one end of the first filter, wherein a pass band of the second filter is in a frequency band higher than a pass band of the first filter, and bulk wave radiation frequencies of all of the first and second resonators of the first filter are higher than the pass band of the second filter.

Abstract: An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO3 substrate. When Euler Angles of the LiNbO3 substrate are within a range of about 0°±5°, within a range of about ?±1.5°, within a range of about 0°±10°, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and ? of the Euler Angles satisfy ?=?0.05°/(T/r?0.04)+31.35°.

Abstract: An acoustic wave device includes a piezoelectric substrate made of LiNbO3, and a dielectric film provided on the piezoelectric substrate to cover first and second IDT electrodes on the piezoelectric substrate. The first and second IDT electrodes include main electrode layers. When wave lengths determined by electrode finger pitches of the first and second IDT electrodes are ?1 and ?2, respectively, the average value thereof is ?0, ?1/?0=1+X, and ?2/?0=1?X, a relationship of 0.05?X?0.65 is satisfied. The wavelength ?1 is the longest, and the wavelength ?2 is the shortest. In Euler angles (?, ?, ?) of the piezoelectric substrate, ? is 0°±5°, ? is 0°±10°, and ? satisfies Expression 1, wherein a relationship of B1<T×r?0.10?0 and B2<T×r?0.10?0 are satisfied.

Abstract: An elastic wave device includes an LiNbO3 substrate, a first elastic wave resonator including a first IDT electrode and a first dielectric film, and a second elastic wave resonator including a second IDT electrode and a second dielectric film. A Rayleigh wave travels along at least one surface of the elastic wave device. A thickness of the first dielectric film differs from a thickness of the second dielectric film. A propagation direction of an elastic wave in the first elastic wave resonator coincides with a propagation direction of an elastic wave in the second elastic wave resonator. Euler angles of the LiNbO3 substrate fall within a range of (0°±5°, ?, 0°±10°).

Abstract: An acoustic wave device includes a piezoelectric substrate made of LiNbO3, and a dielectric film provided on the piezoelectric substrate to cover first and second IDT electrodes on the piezoelectric substrate. The first and second IDT electrodes include main electrode layers. When wave lengths determined by electrode finger pitches of the first and second IDT electrodes are ?1 and ?2, respectively, the average value thereof is ?0, ?1/?0=1+X, and ?2/?0=1?X, a relationship of 0.05?X?0.65 is satisfied. The wavelength ?1 is the longest, and the wavelength ?2 is the shortest. In Euler angles (?, ?, ?) of the piezoelectric substrate, ? is 0°±5°, ? is 0°±10°, and ? satisfies Expression 1, wherein a relationship of B1<T×r?0.10?0 and B2<T×r?0.10?0 are satisfied.

Abstract: A bandpass acoustic wave filter device includes an IDT electrode and a dielectric film disposed on a piezoelectric substrate including a LiNbO3 layer, and an acoustic wave resonator is defined by the IDT electrode. The acoustic wave resonator utilizes the Rayleigh wave, and a response of an SH wave excited by the acoustic wave resonator is outside a pass band of the acoustic wave filter device.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate and includes a main electrode layer. In the IDT electrode, a central region, first and second low acoustic velocity regions and first and second high acoustic velocity regions are disposed in this order. A duty ratio in the first low acoustic velocity region of first electrode fingers and the second low acoustic velocity region of second electrode fingers is larger than a duty ratio in the central region. The main electrode layer includes any one of Au, Pt, Ta, Cu, Ni, and Mo as a main component.

Abstract: An elastic wave device using the S0 mode of plate waves includes a support substrate, an acoustic reflective layer laminated on the support substrate, a piezoelectric body laminated on the acoustic reflective layer, and an IDT electrode disposed on the piezoelectric body. In the acoustic reflective layer, T1+T2 is between about 0.40 and about 0.60 inclusive in a portion in which low and high acoustic impedance layers are adjacent in the laminating direction. T1 is the thickness of the low acoustic impedance layers. T2 is the thickness of the high acoustic impedance layers. T1/(T1+T2) is between about 0.35 and about 0.65 inclusive.

Abstract: An elastic wave device includes a piezoelectric substrate made of LiNbO3, an IDT electrode on the piezoelectric substrate, and a dielectric film on the piezoelectric substrate and covering the IDT electrode. The IDT electrode includes a first electrode layer on or above the piezoelectric substrate and including W or an alloy including W, and a second electrode layer on or above the first electrode layer. A thickness of the first electrode layer is not smaller than 0.062?, ? being a wavelength determined by a pitch of electrode fingers of the IDT electrode. The piezoelectric substrate has Euler angles of (0°± about 5°, ?, 0°± about 10°), ? being not smaller than 8° and not larger than 32°.

Abstract: An acoustic wave device includes a support substrate having a thickness in a first direction, a piezoelectric layer on the support substrate, an interdigital transducer electrode on the piezoelectric layer and including first and second electrode fingers, the first electrode fingers extending in a second direction crossing the first direction, the second electrode fingers extending in the second direction and facing the first electrode fingers in a third direction orthogonal or substantially orthogonal to the second direction, and a reinforcing film on the piezoelectric layer. The support substrate and the piezoelectric layer include a hollow therebetween at a position overlapping the interdigital transducer electrode in the first direction. At least one through hole penetrates the piezoelectric layer at a position not overlapping the interdigital transducer electrode in the first direction, and the through hole communicates with the hollow. The reinforcing film overlaps the hollow in the first direction.

Abstract: A bandpass acoustic wave filter device includes an IDT electrode and a dielectric film disposed on a piezoelectric substrate including a LiNbO3 layer, and an acoustic wave resonator is defined by the IDT electrode. The acoustic wave resonator utilizes the Rayleigh wave, and a response of an SH wave excited by the acoustic wave resonator is outside a pass band of the acoustic wave filter device.

Abstract: An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO3 substrate. When Euler Angles of the LiNbO3 substrate are within a range of about 0° ± 5°, within a range of about ? ± 1.5°, within a range of about 0° ± 10°, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and ? of the Euler Angles satisfy ? = -0.05°/(T/r - 0.04) + 31.35°.

Abstract: An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO3 substrate. When Euler Angles of the LiNbO3 substrate are within a range of about 0°±5°, within a range of about ?±1.5°, within a range of about 0°±10°, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and ? of the Euler Angles satisfy ?=?0.05°/(T/r?0.04)+31.35°.

Abstract: An elastic wave device includes a supporting substrate, an acoustic reflection layer on the supporting substrate, a piezoelectric layer on the acoustic reflection layer, and an IDT electrode on the piezoelectric layer. The acoustic reflection layer includes three or more low-acoustic impedance layers and two or more high-acoustic impedance layers. At least one of a first relationship in which in which, a film thickness of a first low-acoustic impedance layer closest to the piezoelectric layer is thinner than a film thickness of a low-acoustic impedance layer closest to the first low-acoustic impedance layer, and a second relationship in which a film thickness of a first high-acoustic impedance layer closest to the piezoelectric layer is thinner than a film thickness of a high-acoustic impedance layer closest to the first high-acoustic impedance layer, is satisfied.